The objectives of the study are: To assess the effects on tests of intelligence and behavior of phenobarbital, commonly prescribed anticonvulsant in children, and to compare those effects with possible effects of recurrent seizures. The design of this study will permit comparison of measures of tested intelligence and of behavior in children with febrile seizures who have been treated with phenobarbital, and in a group of seizure-free control children. A comparison of the groups should allow assessment of benefit and risk of treatment in a common childhood neurologic problem.